1. Field of the Invention
The present invention relates to a method and a system for supplying circuit components, such as electric-circuit or electronic-circuit components, and particularly to the art of improving the efficiency and/or accuracy of supplying of circuit components.
2. Related Art Statement
Japanese Patent Application laid open for inspection purposes under Publication No. 7(1995)-101487 discloses a circuit-component ("CC") supplying system which supplies a CC carrier tape which carries many CCs. The disclosed system includes a plurality of CC feeders each of which includes an elongate main body and a reel holder which is provided at one of lengthwise opposite end portions of the main body and holds a tape reel around which a CC carrier tape is wound such that the tape reel is rotatable about an axis line parallel to a widthwise direction of the main body. Each CC feeder further includes a tape feeding device which is provided at the other end portion of the main body and feeds the carrier tape at a regular pitch which is equal to a regular distance at which the CCs are arranged on the tape so that the leading one of the CCs carried on the carrier tape is moved to a CC-supply portion of the main body. The CC feeders are attached to a support table such that the respective CC-supply portions thereof are arranged along a straight line, and the support table is moved in a direction parallel to the straight line so that each of the respective CC-supply portions of the CC feeders can selectively be positioned at a CC supplying position.
The above CC supplying system can supply many sorts of CCs to a CC mounting device, such as one which includes an intermittently rotatable body which is intermittently rotatable about a vertical axis line at a first regular angular pitch, and a plurality of CC holding heads which are provided on the rotatable body such that the CC holding heads are angularly spaced from each other at a second regular angular pitch equal to the first angular pitch, or one which includes at least one CC holding head and is movable, in a horizontal plane, in a direction perpendicular to the direction of movement of the support table.
However, in the above CC supplying system, when the support table is moved and stopped to position the CC-supply portion of each CC feeder at the CC supplying position, the tape feeding device, the reel holder, and the tape reel of the each CC feeder are moved as well. That is, the total mass of the movable elements is great. Therefore, if the acceleration and deceleration at which the CC-supply portions are moved are increased to decrease the time needed for each CC-supply portion to be positioned at the CC supplying position, i.e., time needed for the each CC-supply portion to be moved to, and stopped at, the CC supplying position, the each CC-supply portion will vibrate, which results in lowering the accuracy of positioning thereof and the accuracy of supplying of CCs. If the acceleration and deceleration are decreased, the vibration will be decreased. In the latter case, however, the time needed for positioning each CC-supply portion will be increased, which results in lowering the efficiency of supplying of CCs. In particular, since recently there has been a tendency toward using large-diameter tape reels for reducing the number of replacing of tape reels per unit time and therefore the mass of each tape reel is great, it is difficult to improve the efficiency of supplying of the CCs and/or the accuracy of positioning of the CC-supply portions. When the CCs have been consumed on each CC feeder, the current CC supplying operation of the CC supplying system must be interrupted to replace the CC feeder having the consumed tape reel with a new CC feeder. This leads to lowering the efficiency of supplying of CCs. In order to minimize the lowering of the efficiency, the large-diameter tape reels are employed to maximize the number of CCs that are held by each CC feeder and minimize the number of replacing of feeders. Hence, there occurs the problem that the total mass of the movable elements is great.
In addition, if the width of the reel holder of each CC feeder is greater than that of the main body thereof including the tape feeding device, the width of the each CC feeder depends on the width of the reel holder thereof and, even if the width of the main body may be small, the width of the each CC feeder may be great. Accordingly, the support table for supporting the CC feeders needs a great dimension, which leads to increasing the total mass of the movable elements and thereby lowering the accuracy and efficiency of supplying of CCs.
In the above case, the distance between the respective CC-supply portions of each pair of adjacent CC feeders is great. If each CC-supply portion is moved at increased acceleration and deceleration to be positioned at the CC supplying position in a reduced time, the accuracy of supplying of CCs are lowered; on the other hand, if each CC-supply portion is moved at decreased acceleration and deceleration to prevent the lowering of the accuracy of supplying of CCs, the efficiency of supplying of CCs is lowered.
When the CCs have consumed on each CC feeder, new CCs must be supplied. To this end, the current movement of the support table must be stopped for replacing the each CC feeder with a new CC feeder, or the tape reel thereof with a new tape reel. Since the supplying of CCs is interrupted, the efficiency of supplying of CCs is lowered.
Since the tape reels are formed of a soft material such as paper or plastics and accordingly the dimensions thereof include some deviations, there may be left a small space between each tape reel and the reel holder of each CC feeder. Hence, if the each CC feeder vibrates when the support table is moved, the each tape reel will collide with the reel holder, which leads to generating noise.